I actually like this idea much more than a traditional mobile review website.

The key difference is:

GSMArena = Product Review Website
Your idea = Local Used Mobile Price Database

Those are completely different SEO businesses.

If executed correctly, I would rate this:

Idea	Score (/100)
Govt Jobs + Salary	94
Used Mobile Price by City	89
Traditional Mobile Review	69

The used smartphone market is growing rapidly in India's Tier-2 and Tier-3 cities, making local pricing and availability increasingly valuable. (The New Indian Express)

Your page hierarchy

I actually like this architecture.

Used Mobiles Price in Sasaram

↓

Apple
Samsung
Vivo
Realme
OnePlus

↓

Used Apple Mobiles Price in Sasaram

↓

iPhone 16
iPhone 15
iPhone 14
iPhone 13

↓

Used iPhone 15 Price in Sasaram

That is a clean SEO silo.

I would improve it further

Level 1

Used Mobiles Price in Sasaram

Include

✓ Average used mobile price

✓ Cheapest phone

✓ Premium phone

✓ Average age

✓ Most searched models

✓ Popular brands

✓ Filters

Brand

RAM

Storage

Condition

Battery

Level 2

Used Samsung Phones in Sasaram

Show

Galaxy S

Galaxy A

Galaxy M

Galaxy F

Average resale price

Level 3

Used Samsung S24 Price in Sasaram

Instead of only showing

₹39,000

I would show

Expected Price

Excellent

Good

Average

Poor

Screen Broken

Battery <80%

With Bill

Without Bill

Warranty

Box Available

Charger Included

That becomes genuinely useful.

Even better

Build your own

Used Mobile Price Index

Example

iPhone 15

New Price

₹69,999

↓

Average Used Price

₹51,800

↓

6 month trend

₹58k

↓

12 month trend

₹51k

↓

Expected depreciation

26%

↓

Price likely after Diwali

₹48k

That is information people cannot get from a normal classified listing.

Pillar pages

This is where you beat many marketplaces.

Example

Used iPhone 15 Price in Sasaram

↓

Specifications

↓

Camera

↓

Battery

↓

Display

↓

Processor

↓

Gaming

↓

Known Issues

↓

Should You Buy Used?

↓

Things to Check

↓

Repair Cost

↓

Accessories

↓

Amazon Price

↓

Cashify Buyback

↓

Related Phones

Now the page satisfies both transactional and informational intent.

What NOT to do

Do not scrape listings from marketplaces.

Instead

Create your own structured data.

Example

Expected price

Minimum observed price

Maximum observed price

Average price

Typical condition

Price trend

If you eventually use marketplace data, ensure you comply with their terms and avoid copying listings or descriptions. A better long-term asset is your own pricing model and original content. Platforms such as Quikr have historically built resale-price estimation models (MSP) from listing data, showing there is value in estimated pricing rather than just displaying ads. (Digit)

Revenue

I like your funnel.

SEO

↓

Used Mobile Page

↓

Amazon

(New Phone)

↓

Cashify

(Sell Phone)

↓

Accessories

↓

Insurance

↓

Repair

↓

Adsense

You can monetize users whether they're buying new, selling old, or researching prices.

Even better pages

Instead of

Used Mobiles Price in Sasaram

also build

Best Used Phones under ₹10,000 in Sasaram

Best Used iPhone in Sasaram

Best Used Camera Phone in Sasaram

Best Used Gaming Phone in Sasaram

Used 5G Phones in Sasaram

Used Phones under ₹5,000 in Sasaram

Used Phones under ₹15,000 in Sasaram

Used Flagship Phones in Sasaram

Where to Buy Used Phones in Sasaram

How to Check a Used Phone Before Buying

Those pages target additional long-tail searches and naturally link back to your brand and model pages.

One idea that I think is even stronger

Based on everything you've shared over the past year—your strength in programmatic SEO, structured CMS design, and local pages—I would not position this as a classified site like OLX.

Instead, I'd build it as India's Used Mobile Price Intelligence Platform.

Imagine every model page showing:

Estimated fair price (Good, Excellent, Like New)
City-wise average price
30-day, 90-day, and 1-year price trend
Depreciation chart
Repair cost estimates (screen, battery, back glass)
Battery health guide
Original launch price vs. current value
New price from Amazon/Flipkart
Refurbished price from Cashify
"Should you buy used or new?" recommendation

That creates an information moat that's much harder to copy than a standard list of ads, and it complements your existing expertise in building large, structured, data-driven websites.